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Prior Antibiotics Linked to Increased Risk of New Diverticulitis in Older Adults

Key findings

  • This study analyzed data about antibiotic use and new onset of diverticulitis for 29,168 participants in the prospective Nurses' Health Study, average age 72
  • Antibiotic use during the past four years (regardless of age), during mid-life (ages 40–59) and during late adulthood (ages 60+) was independently associated with increased risk of a first episode of diverticulitis
  • A joint analysis of antibiotic use in mid- and late adulthood demonstrated a possible additive/synergistic effect among participants with more frequent use across both time periods
  • If validated, these data will reinforce the importance of appropriate prescribing of antibiotics across the life course

Medications have long been considered a potential factor underlying the increasing incidence of diverticulitis and diverticular-related disorders in Western countries. A prime example is antibiotics because the gut microbiome recovers slowly—and sometimes incompletely—from antibiotic treatment.

Long H. Nguyen, MD, MS, instructor in the Division of Gastroenterology at Massachusetts General Hospital, Andrew T. Chan, MD, MPH, director of cancer epidemiology in the Mass General Cancer Center, chief of the Clinical and Translational Epidemiology Unit in the Department of Medicine and vice chief for clinical research in the Division of Gastroenterology, and colleagues recently conducted the first study of how antibiotic use over the life course influences the subsequent risk of diverticulitis. In the published findings on Gastroenterology, they report that among women, antibiotic use in mid- and late adulthood and recent antibiotic use regardless of age were independently associated with new-onset diverticulitis.

Study Methods

The team used data from the Nurses' Health Study, an ongoing prospective cohort study of 121,700 U.S. female registered nurses who were ages 30–55 at enrollment in 1976. Every two years the participants complete questionnaires on demographics, lifestyle factors, medical diagnoses, medication usage and other exposures of interest.

For this analysis, the study population was 29,168 participants, average age 72, who had no history of acute colonic diverticulitis at study baseline in 2008. They were followed through 2014.

Results

A total of 846 participants reported a first episode of diverticulitis—an incidence rate of 473 cases per 100,000 person-years.

Risk of diverticulitis by cumulative antibiotic use in the past four years, compared with nonuse (multivariable analysis adjusted for known risk factors):

  • 1 to 14 days—RR, 1.26
  • 15 days to 2 months—RR, 1.40
  • >2 months—RR, 1.63 (P for trend <0.0001)

Risk of diverticulitis by cumulative antibiotic use in mid-adulthood (ages 40–59):

  • 1 to 14 days—RR, 1.40
  • 15 days to 2 months—RR, 1.42
  • >2 months—RR, 1.64 (P for trend = 0.03)

Risk of diverticulitis by cumulative antibiotic use in late adulthood (ages 60+):

  • 1 to 14 days—RR, 1.48
  • 15 days to 2 months—RR, 1.70
  • >2 months—RR, 1.75 (P for trend <0.0001)

Antibiotic use in early adulthood (ages 20–39) did not increase the risk of diverticulitis.

A joint analysis of antibiotic use in mid- and late adulthood demonstrated a possible additive/synergistic effect among participants with more frequent use across both time periods.

Implications for Patient Care

These results suggest exposure to antibiotics as early as the fourth decade of life may persistently increase an individual's susceptibility to diverticulitis. The observation that recent, mid-life and late-adulthood antibiotic use all were linked to increased risk might support a causal relationship. If validated, these data will reinforce the importance of appropriate prescribing of antibiotics across the life course.

63%
higher risk of diverticulitis in women with cumulative antibiotic use >2 months in the past four years, compared with nonusers

64%
higher risk of diverticulitis in women with cumulative antibiotic use >2 months during midlife, compared with nonusers

75%
higher risk of diverticulitis in women with cumulative antibiotic use >2 months during late adulthood, compared with nonusers

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Naomi M. Sell, MD, MHS, Rocco Ricciardi, MD, MPH, and colleagues in the Section of Colon and Rectal Surgery, caution that women with diverticulitis represent a vulnerable population that may benefit from a more intensive evaluation.

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Using two large prospective U.S. cohorts, Andrew T. Chan, MD, MPH, Chief of the Clinical Translational Epidemology Unit and Vice-chair of the Division of Gastroenterology, and colleagues observed an inverse association between bowel movement frequency and risk of diverticulitis in both women and men.